This invention is directed to a coating composition and in particular a clear coating composition used for refinishing clear coat/color coat finish of a vehicle such as an automobile or a truck.
Clear coat/color coat finishes for automobiles and trucks have been used in recent years and are very popular. Kurauchi et al U.S. Pat. No. 4,728,543 issued Mar. 1, 1988 and Benefiel et al U.S. Pat. No. 3,639,147 issued Feb. 1, 1972 show the application of a clear coat to a color coat or basecoat in a "wet on wet" application, i.e., the clear coat is applied before the color coat is completely cured.
Productivity of conventional refinish operations using these clear coat/color coat finishes has been lacking in that the conventional refinish clear coating in current use does not dry to a tack free state in relatively short period of time and the vehicle cannot be moved without having foreign particles stick to the clear coat nor can the clear coat be buffed until completely dried to form a finish with acceptable gloss and smoothness. In a typical refinish operation, after the color coat is applied, the clear coat is applied to the vehicle and the resulting finish is allowed to dry before the vehicle is moved. Before any further work can be done to the finish, it must be tack free and must be sufficiently hard to buff to improve gloss or remove minor imperfections. Conventional finishes have long drying and curing times and therefore, reduce the productivity of a refinish operation since the vehicles cannot be moved and worked on quickly after application of the finish.
Also, there is a continued need to use compositions with low VOC (volatile organic content) to meet pollution regulations. It is well known that coating compositions that have a reduced VOC have a high viscosity which reduces the ease of sprayability and application of the composition. To reduce the viscosity of such a composition the molecular weight of the film forming polymer of the composition must be reduced. This further lengthens drying and curing times and reduces the productivity of a refinish operation.
The coating composition of this invention which generally is used as a clear coating dries in a relatively short period of time to a tack-free state and to a hard and glossy finish which allows the vehicle to be moved and the finish can be buffed if necessary and the composition has a lower VOC than conventional compositions in current use. The productivity of a refinish operation using this coating composition can be significantly improved.